无法直接从VM中删除vCPU， 但您可以通过关闭VM后再删除vCPU；

[root@test-kvm ~]# virsh list --all
Id    Name                           State
----------------------------------------------------
1     generic                        running
10    centos7                        running
[root@test-kvm ~]# virsh setvcpus centos7 1
error: unsupported configuration: failed to find appropriate hotpluggable vcpus to reach the desired target vcpu count
[root@test-kvm log]# virsh setvcpus --config centos7 1

[root@test-kvm log]# virsh destroy centos7
Domain centos7 destroyed

[root@test-kvm log]# virsh start centos7
Domain centos7 started

[root@test-kvm log]# virsh dominfo centos7
Id:             11
Name:           centos7
UUID:           6693189b-0a29-4225-b822-724001270bc0
OS Type:        hvm
State:          running
CPU(s):         1
CPU time:       3.3s
Max memory:     4194304 KiB
Used memory:    4194304 KiB
Persistent:     yes
Autostart:      disable
Managed save:   no
Security model: none
Security DOI:   0